Anybody who believes hookahs are more dangerous than the equivalent in cigarettes/cigars/traditional pipes probably doesn't know much about them. Anybody who believes hookahs are healthy probably doesn't know much about them.

The fact is smoking a hookah can carry significant risk which varies with how it is smoked. Even the glycerol that everyone points to as a reason for it being healthier is dangerous if overheated (acrolein is not friendly stuff). Unfortunately as pointed out above, there is a lack of unbiased accurate studies done on hookahs as smoked by humans (I wonder if monkeys would smoke them the same...hmmm...).

It's your body, do what you will with it, especially in a time where everything is a health risk to you, even water and sunlight.